The Pharmacology Core will provide a laboratory that will perform plasma and/or urine measurements of nucleoside analogs used in the treatment of HIV infection and antifungal agents used to treat opportunistic infections associated with AIDS. These measurements will be performed with the aid of analytical instruments and techniques, such as, high performance liquid chromatography, fluorescence polarization immunoassay, gas chromatography- mass spectrometry, and bioassays. The data from these measurements will be used to assess the pharmacokinetic disposition of the compounds which should aid the design of better therapeutic dosage regimens and the detection of possible drug interactions. Our specific aims include: 1. To describe inventory and storage procedures for samples. 2. To assess the pharmacokinetics of nucleoside analogs used in the treatment of HIV infection and anti-fungal agents used in the treatment of opportunistic infections associated with AIDS. 3. To describe the feasibility of assaying 500-1000 samples per year. 4. To describe our participation in quality assurance programs. 5. To show the capability of our laboratory to develop and implement new relevant analytical techniques.